Compositions with coated carbon fibers and methods for manufacturing compositions with coated carbon fibers

ABSTRACT

The present disclosure provides compositions including a carbon fiber material comprising one or more of dibromocyclopropyl or polysilazane disposed thereon; and a thermosetting polymer or a thermoplastic polymer. The present disclosure further provides metal substrates including a composition of the present disclosure disposed thereon. The present disclosure further provides vehicle components including a metal substrate of the present disclosure. The present disclosure further provides methods for manufacturing a vehicle component, including contacting a carbon fiber material with a polysilazane or a dibromocarbene to form a coated carbon fiber material; and mixing the coated carbon fiber material with a thermosetting polymer or a thermoplastic polymer to form a composition. Methods can further include depositing a composition of the present disclosure onto a metal substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure claims benefit of and priority to U.S.application Ser. No. 15/792,125 filed Oct. 24, 2017. The aforementionedpatent application is hereby incoroporated by reference in its entirety.

FIELD

Aspects of the present disclosure provide compositions including coatedcarbon fibers, metal substrates having compositions disposed thereon,vehicle components having a metal substrate, methods for manufacturing avehicle component by contacting a carbon fiber material with apolysilazane or a dibromocarbene and depositing a composition of thepresent disclosure onto a metal substrate.

BACKGROUND

Coatings that prevent metal corrosion are of importance in manyindustries. Metal corrosion costs U.S. industries more than $200 billionannually. Metal surfaces are important in aircraft design because theyoffer improved toughness as compared to ceramics. Advanced joiningtechniques such as laser and friction welding, automated rivetingtechniques, and high-speed machining also make metallic structures moreaffordable than ceramics.

Corrosion of a metal surface can be inhibited or controlled byintroducing a protective layer onto the metal surface. Fibers, such ascarbon fibers, are used in material coating layers on aircraft becauseof their strength. However, when carbon fibers, such as graphite, fromcomposites come in contact with an active metal material, such asaluminum, corrosion can be initiated through a galvanic interactionwhere oxygen reduced at the graphite surface encouragescorrosion/oxidation of the metal surface.

To ameliorate this interaction, the metal is separated from the carbonfiber coating using one or more insulating fiberglass layers, typicallycontaining glass/epoxy or aramid/epoxy. However, use of fiberglassbarriers increases cost of material, fabrication costs, production ratelosses, and increases the weight of the overall structure it becomes apart of, such as an aircraft.

There is a need for carbon fiber coatings that do not promote corrosionof a metal substrate and methods for manufacturing vehicle componentshaving carbon fiber coatings disposed thereon.

SUMMARY

The present disclosure provides a composition including a carbon fibermaterial comprising one or more of dibromocyclopropyl or polysilazanedisposed thereon; and a thermosetting polymer or a thermoplasticpolymer.

In other aspects, a metal substrate includes a composition of thepresent disclosure disposed thereon. A vehicle component can include ametal substrate of the present disclosure.

The present disclosure further provides a method for manufacturing avehicle component including contacting a carbon fiber material with apolysilazane or a dibromocarbene to form a coated carbon fiber material;and mixing the coated carbon fiber material with a thermosetting polymeror a thermoplastic polymer to form a composition.

In other aspects, a method includes depositing a composition of thepresent disclosure onto a metal substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toaspects, some of which are illustrated in the appended drawings. It isto be noted, however, that the appended drawings illustrate only typicalaspects of this present disclosure and are therefore not to beconsidered limiting of its scope, for the present disclosure may admitto other equally effective aspects.

FIG. 1 is an aircraft comprising vehicle components according to oneaspect.

FIG. 2 is a flow diagram of a method for manufacturing components havingpassivated carbon fiber coatings, according to one aspect.

FIG. 3 is a flow diagram of a method for manufacturing components havingpassivated graphite fiber-containing coatings disposed thereon.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of one aspectmay be beneficially incorporated in other aspects without furtherrecitation.

DETAILED DESCRIPTION

The present disclosure provides compositions including a thermosettingor thermoplastic polymer and a coated graphite fiber. The presentdisclosure further provides metal substrates having a composition of thepresent disclosure disposed thereon. As used herein, a metal substrateincludes pure metal substrates and metal-containing substrates. Methodsfor manufacturing metal structures include contacting (e.g.,passivating) a carbon fiber (such as graphite) with a polysilazane ordibromocarbene, mixing the coated carbon fiber with a thermosetting orthermoplastic polymer to form a composition, and depositing thecomposition onto a metal substrate. As used herein, “composition”includes a mixture of components (such as a carbon fiber material and apolysilazane) and/or the reaction product(s) of the components.Compositions and methods of the present disclosure provide corrosioninhibition of a metal substrate and, in aspects where the metalsubstrate is an aircraft component, a composition disposed on a metalsubstrate without the need for an intermediate fiberglass layer betweenthe metal substrate and the composition. Without being bound by theory,compositions of the present disclosure can provide a coating thatinhibits oxygen reduction of a metal substrate by bonding the coating onthe surface of the carbon fiber to form a passivated carbon fiber. Thepassivated carbon fiber provides a barrier to electron transfer to themetal substrate. Carbon fiber coatings can covalently bond to the carbonfiber, unlike conventional approaches, such as fiberglass intermediatelayers, that focus on blocking corrosion/oxidation occurring on themetal surface. This solution solves the galvanic process by inhibitingthe oxygen reduction reaction.

Compositions and Metal Substrates

Compositions of the present disclosure include one or more carbon fibermaterials and one or more polymers. The carbon fiber materials have oneor more dibromocyclopropyls or polysilazanes disposed thereon (e.g.,covalently bonded to the carbon fiber material or non-covalentlyinteracting with the carbon fiber material). Carbon fiber materialincludes carbon fibers and carbon fiber composites. A composite is solidmaterial having at least two phase-separated constituents with differingintrinsic properties. For example, a composite can be a threedimensional structure of fibers, such as carbon fibers, comingledtogether (e.g. woven), can be unidirectional tape, or can be a singleply of material. A composite has a composite structure selected from amat, a tow, a laminate (a layered structure or a ply), a braid, or afilament. Carbon fibers include graphite, graphene, or carbon nanotubes.In at least one aspect, a carbon fiber is graphite.

A polymer of the present disclosure includes at least one of athermosetting polymer or a thermoplastic polymer. In at least oneaspect, a polymer is at least one of an epoxy, a bismaleimide, apolyimide, or a polyaryletherketone. Epoxies are thermosets that canprovide durable coatings on a component, such as a vehicle component,such as an aircraft component. Bismaleimide resins have desirableformability and mechanical properties similar to epoxies and can operateat higher temperatures than epoxies. Polyaryletherketones arethermoplastics that can provide adhesion of a composition of the presentdisclosure to a component and can also withstand chemical, thermal, andphysical conditions experienced by a vehicle if the component is avehicle component. Polyimides have higher strains to failure thanthermoset polymers because thermoplastic polymers can undergo plasticdeformation.

In at least one aspect, a composition of the present disclosure includesthe carbon fiber material from about 1 wt % to about 80 wt %, such asfrom about 20 wt % to about 75 wt %, such as from about 50 wt % to about70 wt %, such as from about 60 wt % to about 65 wt %, based on the totalweight of the composition. In at least one aspect, a composition of thepresent disclosure includes a polymer from about 1 wt % to about 99 wt%, such as from about 5 wt % to about 60 wt %, such as from about 30 wt% to about 60 wt %, such as from about 40 wt % to about 50 wt %, forexample about 35 wt %, based on the total weight of the composition. Thecarbon fiber material of the present disclosure provides strength to thecomposition.

In at least one aspect, a metal substrate includes a composition of thepresent disclosure disposed thereon. Metal substrates include steel,aluminum, titanium, magnesium, tantalum, copper, and alloys thereof. Acomposition can be disposed on a metal substrate, where the compositionhas a thickness of from about 1 micron to about 1 millimeter, such asfrom about 1 micron to about 100 microns, such as from about 1 micron toabout 10 microns. The thickness of a composition of the presentdisclosure disposed on a substrate can be sufficiently thin so as not toadd significant weight to the coated substrate but nonetheless providean adequate amount of composition to provide other benefits, such ascorrosion protection of the substrate. A metal substrate can be, or forma component of, a vehicle component. A vehicle component is a componentof a vehicle, such as a structural component, such as landing gear(s), apanel, or joint, of an aircraft. Examples of a vehicle component includea rotor blade, an auxiliary power unit, a nose of an aircraft, a fueltank, a tail cone, a panel, a coated lap joint between two or morepanels, a wing-to-fuselage assembly, a structural aircraft composite, afuselage body-joint, a wing rib-to-skin joint, and/or other internalcomponent.

FIG. 1 is an aircraft comprising vehicle components, according to atleast one aspect of the present disclosure. As shown in FIG. 1 ,aircraft 100 includes an aircraft structure 102 including vehiclecomponents such as an elongated body 104, a wing 106 extending laterallyfrom the body 104, and a tail 108 extending longitudinally from the body104. Compositions of the present disclosure can be disposed on one ormore surfaces of these aircraft components to form one or more aircraftcomponent(s) having a composition disposed thereon.

Alternatively, compositions of the present disclosure can be disposed onone or more surfaces of wind turbines, satellites, or other vehiclessuch as cars, boats, and the like.

Carbon Fiber Formation

Fibers of the present disclosure include graphene, graphite, and carbonnanotubes. In at least one aspect, a carbon fiber is graphite. FIG. 2 isa flow diagram of a method 200 for manufacturing vehicle componentshaving passivated graphite fiber-containing coatings disposed thereon.Graphite can be produced from a polyacrylonitrile fiber. As shown atblock 202, method 200 includes producing polyacrylonitrile (PAN) (anacrylic textile fiber) by wet spinning or dry spinning of the PANpolymer. Dry spinning produces round smooth fibers whereas wet spinning(extrusion into a coagulating bath) produces a variety of “non-circular”cross-sections, including dog-bone, elliptical, and kidney-shapedcross-sections. These non-circular cross-sections provide largerrelative surface area to improve effective bonding. The fibers can bestretched during the spinning process. The greater the stretch, thesmaller the fiber diameter and the higher the preferred orientation ofthe molecular chain along the fiber axis, resulting in a stiffer carbonfiber when processed. PAN fiber tows can contain from about 10³ fibersto about 10⁵ fibers, for example about 10⁴ fibers. To form the carbonfibers (e.g., graphite), PAN is first stabilized in air at about 250° C.by oxidation. At this point, PAN has a glass transition temperature (Tg)sufficient to resist melting at higher temperatures. The fibers aremaintained under tension during the stabilization to prevent them fromcontracting during oxidation and, through the resulting deformation, toalign further into a ladder structure with the fiber axis. The materialis then carbonized at a temperature from about 1200° C. to 1600° C. inan inert atmosphere, such as inert gas, such as a nitrogen. As this heattreatment proceeds, benzene aromatic rings link to form polynucleararomatic fragments (e.g., a more graphite-like structure). Gradually thearomatic network transforms to mainly carbon atoms and becomes denserthrough cross-linking with the evolution of N₂ through open pores in thefiber. If the heat treatment is performed at 1500-1600° C., the straincapability of the fibers is then over 1.5% with an intermediate value ofthe Young's modulus of around 240 GPa.

If a higher modulus is desired, which will lower strength and straincapability of the fibers, the fibers can undergo a final graphitizationstage of heat treatment. As shown at block 204, method 200 includesintroducing the fibers into a furnace (such as a graphitization furnace)and heating the furnace to a temperature from about 2,000° C. to about2,700° C., for example about 2500° C. The graphitization heat treatmentcan occur in an inert atmosphere, such as inert gas, such as argon,which reduces or prevents the formation of imperfections in the fiber.During this process, the aromatic carbon basal layer planes grow, byfurther coalescence of adjacent layers, resulting in an increase inplanar orientation of the fiber into a fiber having a graphitemorphology, and thus a more elastic modulus (e.g., from about 300 GPa toabout 400 GPa, such as about 380 GPa), as compared to the fiber materialthat has not undergone this graphitization heat treatment. The carbonfibers produced herein can have a filament diameter of from about 1 μmto about 20 μm, such as about 8 μm and can form a tow (bundle offilaments) having from about 2×10⁴ of filaments to about 3×10⁴ offilaments, such as 2.5×10⁴ of filaments. Carbon fibers of the presentdisclosure can have a thickness of from about 1 μm to about 1 mm, suchas from about 1 μm to about 10 μm, and a density of from about 0.5 g/cm³to about 1 g/cm³, such as about 0.7 g/cm³.

Passivating Carbon Fiber

As shown at block 206, method 200 includes coating a carbon fiber.Coating the carbon fiber can include a polysilazane passivation processor a dibromocarbene passivation process.

Polysilazane Passivation

In a polysilazane passivation process, a polysilazane polymer coatingcan be directly applied to a fiber surface. The coating reactant can beapplied directly as a surface finish or the fiber surface can beslightly oxidized to form —OH groups on the fiber. Without being boundby theory, the —OH moieties can be reactive anchors to form covalentbonds with the polymer coating.

Optionally, the first stage of a polysilazane passivation processincludes contacting the carbon fiber (e.g., graphite fiber) with an acidin order to oxidize the surface of the carbon fiber. Strong acidsinclude nitric acid, hydrochloric acid, and sulfuric acid. In at leastone aspect, the acid is nitric acid. In at least one aspect, contactingthe carbon fiber with an acid includes dipping the carbon fiber into asolution of the acid. The concentration of the acid in the solution canbe from about 0.001 moles of acid per liter of water (M) to about 1M,such as from about 0.1 M to about 1 M.

In at least one aspect, the carbon fiber (e.g., graphite fiber) isintroduced to the strong acid soon after the carbon fiber is removedfrom the furnace of block 204 such that the carbon fiber is at elevatedtemperature from the furnace when the carbon fiber is introduced to theacid. This aspect provides reduced production costs by reducing oreliminating reheating (energy consumption) of the carbon fiber upontreatment with an acid.

Immersion time of the carbon fiber in the acid solution can be fromabout 0.5 seconds to about 1 minute, for example about 10 seconds. Thecarbon fiber is removed from the acid solution at a rate from about 0.1m/min to about 10 m/min, for example about 0.3 m/min.

The second stage of a polysilazane passivation process includesdissolving the polysilazane in an organic solvent. Organic solventsinclude ethers and aromatic hydrocarbons. In at least one aspect, thepolysilazane is dissolved at 20 wt % in dibutylether. In at least oneaspect, a polysilazane is cross-linked in solution by, for example,adding 3 wt % of dicumyl peroxide (DCP) and 0.015 wt % of platinum tothe polysilazane.

The polysilazane solution is then applied (passivated) to the carbonfiber by, for example, spraying or dipping. Residense time for applyingthe polysilazane solution can be from about 30 seconds to about 10minutes. The polysilazane can be applied to the carbon fiber at anamount of from about 0.001 mg polysilazane/mm² of carbon fiber to about1 g polysilazane/mm² of carbon fiber, such as from about 0.003 mg/mm² toabout 0.007 mg/mm², for example about 0.0038 mg/mm² or 0.0064 mg/mm² toprovide a coating sufficient to mask the corrosive effect ofoxygen-containing moieties (if any) present on the graphite.

After passivation, the graphite sample is thermally treated at atemperature from about 500° C. to about 700° C. with a heating rate ofabout 5° Kelvin/min. In at least one aspect, the passivated carbon fiberis thermally treated from about 1 minute to about two hours to removeany volatiles from the passivated carbon fiber whilemaintaining/promoting the graphite structure. Thermal treatment can beperformed by a continuous infrared furnace.

Polysilazanes can be obtained commercially, such as from ClariantFinance (BVI) Limited. In at least one aspect, a polysilazane isrepresented by formula (I):

—(SiR¹R²—NR³)_(n)—  (I)

where R¹, R² and R³ are independently selected from hydrogen or alkyl,aryl, vinyl or (trialkoxysilyl)alkyl, where n is a positive integer andthe polysilazane has a number-average molecular weight of from about 150g/mol to about 150,000 g/mol.

In at least one aspect, each of R¹, R² and R³ is independently selectedfrom hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl,tert-butyl, phenyl, tolyl, vinyl, 3-(triethoxysilyl)propyl and3-(trimethoxysilylpropyl).

In at least one aspect, R¹, R² and R³ are each hydrogen.

In at least one aspect, a polysilazane is represented by formula (II):

—(SiR¹R²—NR³)_(n)—(SiR⁴R⁵—NR⁶)_(p)—  (II)

where R¹, R², R³, R⁴, R⁵ and R⁶ are independently selected fromhydrogen, alkyl, aryl, vinyl or (trialkoxysilyl)alkyl and n and p areeach a positive integer and the polysilazane has a number-averagemolecular weight of from about 150 g/mol to about 150,000 g/mol.

In at least one aspect, R¹, R³, and R⁶ are hydrogen and R², R⁴ and R⁵are methyl.

In at least one aspect, R¹, R³, and R⁶ are hydrogen, R² and R⁴ aremethyl, and R⁵ is vinyl.

In at least one aspect, R¹, R⁴, and R⁶ are hydrogen, and R² and R⁵ aremethyl.

In at least one aspect, a ratio of n to p is from about 2:1 to about4:1.

In at least one aspect, a polysilazane is represented by formula (III):

—(SiR¹R²—NR³)_(n)—(SiR⁴R⁵—NR⁶)_(p)—(SiR⁷R⁸—NR⁹)_(q)   (III)

where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, and R⁹ are independently selectedfrom hydrogen, alkyl, aryl, vinyl or (trialkoxysilyl)alkyl and n, p, andq are each a positive integer and the polysilazane has a number-averagemolecular weight of from about 150 g/mol to about 150,000 g/mol.

In at least one aspect, R¹, R³, and R⁶ are hydrogen, R², R⁴, R⁵ and R⁸are methyl, R⁹ is (triethoxysilyl)propyl and R⁷ is alkyl or hydrogen.

In at least one aspect, a method for passivating a carbon fiber materialincludes contacting a carbon fiber (e.g., graphite fiber) with an acid.The method includes dissolving a polysilazane in an organic solvent toform a solution and applying the solution to the carbon fiber by, forexample, spraying or dipping. The method includes thermally treating thepassivated carbon fiber material at a temperature from about 500° C. toabout 700° C. with a heating rate of about 5° Kelvin/min.

In at least one aspect, a carbon fiber material comprises a polysilazanecoating disposed thereon. In at least one aspect, a polysilazane is oris the reaction product of a polysilazane represented by formula (I):

—(SiR¹R²—NR³)_(n)—  (I)

where R¹, R² and R³ are independently selected from hydrogen or alkyl,aryl, vinyl or (trialkoxysilyl)alkyl, where n is a positive integer andthe polysilazane has a number-average molecular weight of from about 150g/mol to about 150,000 g/mol.

In at least one aspect, each of R¹, R² and R³ is independently selectedfrom hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl,tert-butyl, phenyl, tolyl, vinyl, 3-(triethoxysilyl)propyl and3-(trimethoxysilylpropyl).

In at least one aspect, R¹, R² and R³ are each hydrogen.

In at least one aspect, a polysilazane is represented by formula (II):

—(SiR¹R²—NR³)_(n)—(SiR⁴R⁵—NR⁶)_(p)—  (II)

where R¹, R², R³, R⁴, R⁵ and R⁶ are independently selected fromhydrogen, alkyl, aryl, vinyl or (trialkoxysilyl)alkyl and n and p areeach a positive integer and the polysilazane has a number-averagemolecular weight of from about 150 g/mol to about 150,000 g/mol.

In at least one aspect, R¹, R³, and R⁶ are hydrogen and R², R⁴ and R⁵are methyl.

In at least one aspect, R¹, R³, and R⁶ are hydrogen, R² and R⁴ aremethyl, and R⁵ is vinyl.

In at least one aspect, R¹, R⁴, and R⁶ are hydrogen, and R² and R⁵ aremethyl.

In at least one aspect, a ratio of n to p is from about 2:1 to about4:1.

In at least one aspect, a polysilazane is represented by formula (III):

—(SiR¹R²—NR³)_(n)—(SiR⁴R⁵—NR⁶)_(p)—(SiR⁷R⁸—NR⁹)_(q)   (III)

where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, and R⁹ are independently selectedfrom hydrogen, alkyl, aryl, vinyl or (trialkoxysilyl)alkyl and n, p, andq are each a positive integer and the polysilazane has a number-averagemolecular weight of from about 150 g/mol to about 150,000 g/mol.

In at least one aspect, R¹, R³, and R⁶ are hydrogen, R², R⁴, R⁵ and R⁸are methyl, R⁹ is (triethoxysilyl)propyl and R⁷ is alkyl or hydrogen.

Dibromocarbene Passivation

In a dibromocarbene passivation process, dibromocyclopropyl moieties areformed on a fiber surface. The dibromo groups of the fiber surface canbe reacted with other molecules, such as those with diol functionalityto form covalently bonded multilayer coating structures. The dibromogroups of the fiber surface can also be reacted with activated Zn andsubsequent carbonyl-containing substituents.

In a dibromocarbene passivation process, a fiber is added to a benzenebath at an initial concentration of fiber of about 3 mg/mL benzene.Bromoform is then added to the benzene solution (e.g., to aconcentration of 10 mL bromoform/23 mL benzene). An amine-containingphase transfer catalyst (e.g., amine catalyst), such as trihexylamine,is also added to the benzene solution (e.g., to a concentration of 2 mLtrihexylamine/23 mL benzene).

The supernatant of the solution is then added (e.g., dropwise) to astirring aqueous solution of sodium hydroxide (e.g., 0.125 M) to form abiphasic benzene and aqueous sodium hydroxide mixture that is allowed tostir (e.g., from about 24 hours to about 72 hours, for example about 48hours) at a temperature from about 60° C. to about 80° C., for exampleabout 70° C. Without being bound by theory, the addition of aphase-transfer catalyst, trihexylamine, facilitates the migration ofcarbenes generated at the phase boundary by the formation of ylideintermediates. Br₂C⁻N⁺(C₆H₁₃)₃ ylides in turn react with carbon fibers,yielding carbon fibers having dibromocyclopropyl groups. The organicphase of the biphasic mixture is filtered, for example, using a membranefiltration apparatus (e.g., Whatman, Anodisc 200 nm). The residual solidproduct is washed, for example, with toluene and/or tetrahydrofuran andthen resuspended in toluene. This toluene organic phase is thenextracted an additional three times using water (to remove any remainingsalt from the toluene solution) and dried over calcium carbonate ormagnesium sulfate (to remove water present in the organic toluenephase). The obtained toluene organic phase containing thedibromocyclopropyl-functionalized fiber is then dried (e.g., undervacuum and heated).

Preferably, exfoliation/sonication is avoided for a dibromocarbenepassivation process of the present disclosure in order to reduce orprevent the disaggregation of graphite fibers into graphene in examplewhere the carbon fiber used is graphite.

After passivation of a carbon fiber of the present disclosure, the fibercan be evaluated electrochemically by placing the fiber in anelectrolyte (e.g., phosphate buffered saline (PBS)) and scanning thepotential for indication of oxygen reduction current. The ratio of thecurrent measured to the current of a graphite fiber without passivationwill yield a passivation efficiency. Currents can range from microampsto milliamps depending on the surface area of the carbon fiber. Thegalvanic corrosion of passivated graphite fibers of the presentdisclosure can be assessed in a cyclic corrosion chamber according toASTM G85. An air-dried electrode is introduced into a solutioncontaining 3.5% pH 7 PBS Buffer. About 8 mm of a passivated graphite rodis then introduced into the PBS solution. Electrochemical experiments,such as cyclic voltammetry 20 mV/s vs. SCE, are then performed to verifyoxygen reduction reaction inhibition.

In at least one aspect, a method for passivating a carbon fiber materialincludes introducing a carbon fiber material (e.g., graphite) to abenzene bath. The method includes introducing bromoform to the benzenesolution. The method includes introducing an amine-containing phasetransfer catalyst (e.g., amine catalyst), such as trihexylamine to thebenzene solution. The method includes introducing the benzene solutionto an aqueous solution of sodium hydroxide to form a biphasic mixtureand optionally stirring the biphasic mixture. The method includesfiltering the organic phase of the biphasic mixture and washing thesolid product with toluene and/or tetrahydrofuran. The method includesresuspending the solid in toluene. The method includes drying the solidunder vacuum and optionally heating.

In at least one aspect, a carbon fiber material comprises adibromocarbene coating disposed thereon. A dibromocarbene coatingcomprises and/or is the reaction product of one or more dibromocarbenes.

Fiber Composite Formation

At block 208, method 200 includes arranging the passivated fiber into acomposite containing the fibers. A composite has a composite structurethat is a mat, a tow, a laminate (a layered structure or a ply), abraid, or a filament. A composite is arranged during manufacture of thevehicle component with the fibers oriented in one or more directions insufficient concentrations to provide a desired strength and stiffness inthe resulting product form after curing. Fiber tows can be woven toproduce a fabric, such as a plain weave or satin weave cloth. Forin-plane loading, a laminated or plywood type of construction is usedincluding layers or plies of unidirectional or bi-directional orientatedfibers. Alternatively, the fibers are arranged by one or more textiletechniques, such as weaving, braiding, or filament winding.

Thus, to obtain the desired mechanical properties of a fiber, the fiberlayers or plies in a laminate are arranged at angles from about 0° toabout 90° relative to a 0° primary loading direction. In at least oneaspect, a fiber mat has a combination of 0°, +/−45° C., and 90° C.orientations, which reduces or prevents distortion of the componentafter cure and under service loading. The laminate is stiffest andstrongest (in-plane) in the direction with the highest concentration of0° fibers, and the laminate is said to be orthotropic.

When the ply configuration is made of equal numbers of plies at 0°+/−60°or 0°, +/−45°, and 90°, the in-plane mechanical properties do not varymuch with loading direction and the composite is then said to bequasi-isotropic. Because the quasi-isotropic configuration has a stressconcentration factor similar to that of an isotropic material, it isalso used where local stresses are high, such as in a mechanical joint.

In at least one aspect, a fiber composite is cowoven with one or moreadditional fibers/composites. Additional fibers include glass or aramidfibers. In at least one aspect, one or more additional fibers are wovenin the 0° or warp direction (the roll direction) or in the 90° (weft)direction.

In at least one aspect, forming a fiber composite includes holding acarbon fiber in a stationary position using a knitting yarn duringweaving to avoid fiber crimping (waviness). These non-crimp fabrics cancontain fibers orientated at 0°, 90°, and +/−45° in any desiredproportions. Because of the reduction or elimination in fiber waviness,composites based on non-crimp fabric show a significant improvement incompression strength compared with those based on woven materials.Stiffness in both tension and compression is also increased by about 10%as compared with composites based on woven materials.

Composition and Component Formation

At block 210, method 200 includes combining the fiber composite with apolymer to form a composition of the present disclosure. Combiningincludes infiltrating a carbon fiber or carbon fiber composite of thepresent disclosure with a liquid polymer that is then cured/solidified(e.g., by heating or cooling) to form a continuous solid matrix. Forexample, a thermoset is cured by heating or a thermoplastic iscrystallized by cooling. Alternatively, single fibers or a composite offibers (e.g., tows of fibers or sheets of aligned fibers) is coated orintermingled with solid polymer or polymer precursor and the compositionformed by flowing the coatings together (and curing if required) underheat and pressure.

A polymer is a thermosetting or thermoplastic polymer. Thermosettingpolymers are long-chain molecules that cure by cross-linking to form athree dimensional network which does not readily melt or reform. Thesepolymers can provide fabrication of compositions at relatively lowtemperatures and pressures because they pass through a low-viscositystage before polymerization and cross-linking (if any). In at least oneaspect, a polymer is at least one of an epoxy, a bismaleimide, or apolyaryletherketone (such as a polyetheretherketone or apolyetherketone).

Epoxies have sufficient mechanical properties for use as aircraftcoatings, have low shrinkage and form adequate bonds to fibers. Epoxiespass through a low-viscosity stage during the cure, which provides theuse of liquid resin-forming techniques such as resin-transfer molding.Compositions comprising epoxies that cure at 120° C. and 180° C. canhave upper service temperatures of about 100° C. to about 150° C.

Bismaleimide resins have desirable formability and mechanical propertiessimilar to epoxies and can operate at higher temperatures than epoxies.Compositions comprising bismaleimide that cure at about 200° C. can haveupper service temperatures above 180° C.

A polymer of the present disclosure can be a thermoplastic polymer.Thermoplastic polymers are linear (non-crosslinked) polymers that can bemelted and reformed. High-performance thermoplastics for use as aircraftcoatings include polymers such as polyetheretherketone which can becured up to about 120° C., polyetherketone which can be cured up toabout 145° C., and polyimide which can be cured up to about 270° C.Thermoplastic polymers are advantageous because they have higher strainsto failure than thermoset polymers because thermoplastic polymers canundergo plastic deformation.

Because thermoplastic polymers are already polymerized, they can formvery high viscosity liquids when melted. Fabrication techniques can bebased on resin-film (or resin-fiber) infusion and pre-preg techniques.The fibers are coated with the polymer (from a solvent solution) and theresulting part is then consolidated under high temperature and pressure.Alternatively, sheets of thermoplastic film can be layered betweensheets of dry fiber or fibers of thermoplastic can be woven through thecarbon fibers and the composite consolidated by hot pressing.Furthermore, because thermoplastics absorb very little moisture, theyhave better hot/wet property retention than thermosetting composites,but do involve higher temperature processing.

The polymer of the present disclosure forms the shape of the compositionand can transfer load into and out of the fibers, can separate thefibers so adjacent fibers are protected if one fails, and/or can protectthe fiber from the surrounding environment. The fiber can interact with(e.g., bond to) the polymer to provide toughness to the overallcomposition. The location(s) where the fiber interacts with the polymeris known as the interface or interphase.

Combining a fiber or fiber composite with a polymer to form acomposition of the present disclosure includes impregnating or coating(e.g., dipping or spraying) a fiber (or fiber composite) with a liquidpolymer to form a mixture that is then cured. This can be referred to asresin-transfer molding and can be used, for example, if the polymer hasa low-viscosity (e.g., less than 1,000 centipoise (cps)).

Alternatively, combining a fiber (or fiber composite) with a polymer toform a composition of the present disclosure includes infusing a meltedpolymer film into a fiber (or fiber mat) under pressure and then curing.This can be referred to as resin-film infusion.

Alternatively, combining a fiber (or fiber composite) with a polymer toform a composition of the present disclosure includes pre-impregnatingfiber sheet bundles or tows with a liquid resin (pre-preg) forsubsequent arrangement (stacking) followed by consolidation and cureunder temperature and pressure. For thermoset composites starting atroom temperature, the temperature can be increased up to a temperatureof about 350° F.), the pressure of the environment is increased (e.g.,up to about 200 psi), and the high temperature, high pressure conditionis maintained for up to several hours depending on the material, then isallowed to cool to room temperature/ambient pressure.

In at least one aspect, a plurality of cured compositions (e.g., fibersimpregnated or coated with a liquid polymer) are stacked andconsolidated at a temperature from about 250° F. to about 600° F. toform a consolidated composition.

As shown at block 212, method 200 includes depositing a composition ofthe present disclosure onto a metal substrate. Metal substrates includesteel, aluminum, titanium, magnesium, tantalum, copper, and alloysthereof. Depositing can include any suitable “lay up” process or“collation” process known in the art. For example, a composition of thepresent disclosure can be cut to match the shape of a metal substrateand deposited onto the metal. The deposited composition is “debulked” byplacing the deposited composition in a vacuum bag and pulled to apressure of 980 mbar or greater for a time period from about 1 minute toabout 30 minutes. The composition can be deposited as tiles or as acontinuous piece. A breather material can be used and can connect to thevacuum ports of the vacuum bag.

At block 214, the composition is cured, to fabricate a part, such as acoated vehicle component of a vehicle, such as an aircraft, a car, atrain, a boat, or a wind turbine. In at least one aspect, a compositionof the present disclosure is cured at a temperature from about 20° C. toabout 300° C., such as from about 100° C. to about 200° C. A vehiclecomponent is any suitable component of a vehicle, such as a structuralcomponent, such as landing gear(s), a panel, or joint, of an aircraft,etc. Examples of a vehicle component include a rotor blade, an auxiliarypower unit, a nose of an aircraft, a fuel tank, a tail cone, a panel, acoated lap joint between two or more panels, a wing-to-fuselageassembly, a structural aircraft composite, a fuselage body-joint, a wingrib-to-skin joint, and/or other internal component. In at least oneaspect, a vehicle is an aircraft, a car, a train, or a boat. In at leastone aspect, a part is a part of a wind turbine.

FIG. 3 is a flow diagram of a method 300 for manufacturing componentshaving passivated graphite fiber-containing coatings disposed thereon.As shown in FIG. 3 , method 300 introducing a fiber into a furnace(Block 302), introducing an inert gas into the furnace (Block 304), andheating the furnace to a temperature from about 2,000° C. to about2,700° C. (Block 306). Method 300 includes contacting a carbon fibermaterial, such as graphite, with a polysilazane or a dibromocarbene toform a coated carbon fiber material (Block 308). Method 300 includesmixing the coated carbon fiber material with a polymer selected from athermosetting polymer or a thermoplastic polymer to form a composition(Block 310). Method 300 includes depositing the composition onto a metalsubstrate (Block 312). Method 300 includes curing the composition at atemperature from about 20° C. to about 300° C. (Block 314).

Overall, compositions and methods of the present disclosure providecorrosion inhibition of a metal substrate and, in aspects where themetal substrate is an aircraft component, a composition disposed on ametal substrate without the need for an intermediate fiberglass layerbetween the metal substrate and the composition, which reduces theweight of the aircraft from hundreds to thousands of pounds (lbs).

Definitions

The term “alkyl” includes a substituted or unsubstituted, linear orbranched acyclic alkyl radical containing from 1 to about 20 carbonatoms. In at least one aspect, alkyl includes linear or branched C₁₋₂₀alkyl. C₁₋₂₀ alkyl includes methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosanyl, andstructural isomers thereof.

The term “aryl” refers to any monocyclic, bicyclic or tricyclic carbonring of up to 6 atoms in each ring, wherein at least one ring isaromatic, or an aromatic ring system of 5 to 14 carbons atoms whichincludes a carbocyclic aromatic group fused with a 5- or 6-memberedcycloalkyl group. Examples of aryl groups include, but are not limitedto, phenyl, naphthyl, anthracenyl, or pyrenyl.

The term “alkoxy” is RO—wherein R is alkyl as defined herein. The termsalkyloxy, alkoxyl, and alkoxy may be used interchangeably. Examples ofalkoxy include, but are not limited to, methoxyl, ethoxyl, propoxyl,butoxyl, pentoxyl, hexyloxyl, heptyloxyl, octyloxyl, nonyloxyl,decyloxyl, and structural isomers thereof.

Compounds of the present disclosure include tautomeric, geometric orstereoisomeric forms of the compounds. Ester, oxime, onium, hydrate,solvate and N-oxide forms of a compound are also embraced by the presentdisclosure. The present disclosure considers all such compounds,including cis- and trans-geometric isomers (Z- and E-geometric isomers),R- and S-enantiomers, diastereomers, d-isomers, I-isomers, atropisomers,epimers, conformers, rotamers, mixtures of isomers and racemates thereofare embraced by the present disclosure.

The descriptions of the various aspects of the present disclosure havebeen presented for purposes of illustration, but are not intended to beexhaustive or limited to the aspects disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the described aspects.The terminology used herein was chosen to best explain the principles ofthe aspects, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the aspects disclosed herein. While theforegoing is directed to aspects of the present disclosure, other andfurther aspects of the present disclosure may be devised withoutdeparting from the basic scope thereof.

What is claimed is:
 1. A composition comprising: a carbon fiber materialcomprising polysilazane; and a polymer selected from a thermosettingpolymer or a thermoplastic polymer.
 2. The composition of claim 1,wherein the carbon fiber material has a composite structure selectedfrom a mat, a tow, a layered structure, a ply, a braid, or a filament.3. The composition of claim 2, wherein the carbon fiber material isgraphite.
 4. The composition of claim 1, wherein the polymer is anepoxy, a bismaleimide, a polyimide, or polyaryletherketone.
 5. Thecomposition of claim 4, wherein the composition comprises the polymerfrom about 30 wt % to about 60 wt % based on the total weight of thecomposition.
 6. The composition of claim 5, wherein the compositioncomprises the carbon fiber material from about 50 wt % to about 70 wt %based on the total weight of the composition.
 7. A metal substratecomprising the composition of claim 1 disposed thereon.
 8. The metalsubstrate of claim 7, wherein the metal is steel, aluminum, titanium,magnesium, tantalum, copper, or an alloy thereof.
 9. The metal substrateof claim 8, wherein the composition is disposed on the substrate at athickness from about 1 micron to about 100 microns.
 10. A vehiclecomponent comprising the metal substrate of claim
 9. 11. The vehiclecomponent of claim 10, wherein the vehicle component is a rotor blade, alanding gear, an auxiliary power unit, a nose of an aircraft, a fueltank, a tail cone, a panel, a coated lap joint between two or morepanels, a wing-to-fuselage assembly, a structural aircraft composite, afuselage body-joint, or a wing rib-to-skin joint.
 12. A method formanufacturing a component, comprising: contacting a carbon fibermaterial with a polysilazane to form a coated carbon fiber material; andmixing the coated carbon fiber material with a polymer selected from athermosetting polymer or a thermoplastic polymer to form a composition.13. The method of claim 12, further comprising depositing thecomposition onto a metal substrate.
 14. The method of claim 12, whereinthe carbon fiber material comprises graphite, and the method furthercomprises: introducing a fiber into a furnace; introducing an inert gasinto the furnace; and heating the furnace to a temperature from about2,000° C. to about 2,700° C. to form the graphite.
 15. The method ofclaim 12, wherein contacting further comprises contacting the carbonfiber material with an acid.
 16. The method of claim 15, whereincontacting the carbon fiber material with the acid comprises immersingthe carbon fiber material in a solution comprising the acid for fromabout 0.5 seconds to about 1 minute and removing the carbon fibermaterial from the solution comprising the acid at a rate of about 0.3m/min.
 17. The method of claim 15, wherein contacting the carbon fibermaterial with the polysilazane comprises: dissolving the polysilazane ina solvent; and applying an amount of the polysilazane to the carbonfiber material from about from about 0.003 mg polysilazane/mm² of carbonfiber material to about 0.007 mg polysilazane/mm² of carbon fibermaterial.
 18. The method of claim 17, further comprising thermallytreating the carbon fiber material at a temperature from about 500° C.to about 700° C. after applying the polysilazane to the carbon fibermaterial.
 19. The method of claim 15, wherein the polysilazane isrepresented by formula (I):—(SiR¹R²—NR³)_(n)—  (I) wherein: R¹, R² and R³ are independentlyselected from hydrogen, alkyl, aryl, vinyl, or (trialkoxysilyl)alkyl; nis a positive integer, and the polysilazane has a number-averagemolecular weight of from about 150 g/mol to about 150,000 g/mol.
 20. Themethod of claim 15, wherein contacting the carbon fiber material withthe polysilazane comprises: dissolving the polysilazane in a solvent;and applying an amount of the polysilazane to the carbon fiber materialfrom about from about 0.003 mg polysilazane/mm² of carbon fiber materialto about 0.007 mg polysilazane/mm² of carbon fiber material, wherein thepolysilazane is represented by formula (I):—(SiR¹R²—NR³)_(n)—  (I) wherein: R¹, R² and R³ are independentlyselected from hydrogen, alkyl, aryl, vinyl, or (trialkoxysilyl)alkyl; nis a positive integer, and the polysilazane has a number-averagemolecular weight of from about 150 g/mol to about 150,000 g/mol.